Sexual risk reduction interventions to prevent the transmission of HIV also have beneficial effects on other social health concerns, such as non-HIV STDS and unintended pregnancy. Most prior studies of the cost-effectiveness of HIV prevention interventions focus only on the impact of the intervention on HIV outcomes. Studies that neglect the impact of these interventions on other STDs and unintended pregnancies may underestimate the economic benefits of sexual behavior change. Furthermore, little is known regarding the cost-effectiveness of HIV prevention interventions viewed as STD (or unintended pregnancy) prevention programs. This application seeks funding to conduct a cost-effectiveness analysis of a community-level sexual behavior risk reduction intervention that was implemented at multiple locations in the U.S. The intervention targets low-income, predominantly African- American adolescents living in urban housing developments. This analysis will allow us to: 1) estimate the number of HIV and STD infections and the number of unintended pregnancies prevented by the intervention, as well as associated savings in medical care costs and lost economic productivity; 2) evaluate the cost-effectiveness of the intervention with regard to HIV (measured by the cost per HIV case averted), STDs (measured by the cost per chlamydia, gonorrhea, syphilis, HPV, or HBV case averted), and unintended pregnancies (measured by the cost per unintended pregnancy prevented); 3) compare the cost-effectiveness of this intervention with other HIV, STD, and unintended pregnancy prevention interventions; and 4) determine how much difference the addition of non-HIV STDs and unintended pregnancy outcomes make to the estimated HIV prevention cost-effectiveness of the intervention. The proposed, more inclusive, approach to estimating the cost-effectiveness of HIV prevention should produce more accurate estimate for use in policy analyses and resource allocation decision-making.